Conventionally, external preparations for skin have been developed, which focused on prevention and amelioration of skin roughness. Examples of such external preparations for skin include: skin external preparations of ameliorating skin roughness which contains alum, calcium salt and magnesium salt (see Japanese Laid-open Patent Application No. 2004-284962), and an agent for preventing/ameliorating skin roughness which consists of N-α-benzoyl-L-arginine, N-α-benzoyl-L-arginine ethyl ester or salt of N-α-benzoyl-L-arginine ethyl ester (see Japanese Laid-open Patent Application No. 2000-281556).
In addition, it has been known that 5-aminolevulinic acids are used as herbicides (for example, see Japanese Laid-open Patent Application No. 08-081322), plant growth regulators (for example, see Japanese Laid-open Patent Application No. 07-53487), external preparations for head (for example, see Japanese Laid-open Patent Application No. 11-116446), etc.
However, an external preparation for skin for making beautiful skin which contains 5-aminolevulinic acids and the effects of 5-aminolevulinic acids on skin roughness, etc., have not been known.
Patent Document 1: Japanese Laid-open Patent Application No. 2004-284962
Patent Document 2: Japanese Laid-open Patent Application No. 2000-281556
Patent Document 3: Japanese Laid-open Patent Application No. 08-081322
Patent Document 4: Japanese Laid-open Patent Application No. 07-53487
Patent Document 5: Japanese Laid-open Patent Application No. 11-116446